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The higher the proton affinity, the stronger the base and the weaker the conjugate acid in the gas phase.The (reportedly) strongest known base is the ortho-diethynylbenzene dianion (E pa = 1843 kJ/mol), [3] followed by the methanide anion (E pa = 1743 kJ/mol) and the hydride ion (E pa = 1675 kJ/mol), [4] making methane the weakest proton acid [5] in the gas phase, followed by dihydrogen.
Hydrogen cyanide is a weak acid in aqueous solution with a pK a of about 9. In strongly alkaline solutions, above pH 11, say, it follows that sodium cyanide is "fully dissociated" so the hazard due to the hydrogen cyanide gas is much reduced. An acidic solution, on the other hand, is very hazardous because all the cyanide is in its acid form.
For instance, hydrogen fluoride, whether dissolved in water (= 3.2) or DMSO (= 15), has values indicating that it undergoes incomplete dissociation in these solvents, making it a weak acid. However, as the rigorously dried, neat acidic medium, hydrogen fluoride has an H 0 {\displaystyle H_{0}} value of –15, [ 1 ] making it a more strongly ...
Standard hydrogen bonds are asymmetrical, with the hydrogen being associated with one heteroatom. When the pKa between the heteroatoms is equal, a symmetrical hydrogen bond forms with the hydrogen in equilibrium between two locations. At shorter distances, the barrier between the two energy minima is low enough that the hydrogen is equally ...
Dissociation in chemistry is a general process in which molecules (or ionic compounds such as salts, or complexes) separate or split into other things such as atoms, ions, or radicals, usually in a reversible manner.
Hydrogen: 0.2476 0.02661 Hydrogen bromide: 4.510 0.04431 Hydrogen chloride: 3.716 0.04081 Hydrogen cyanide [2] 11.29 0.0881 Hydrogen fluoride [2] 9.565 0.0739 Hydrogen iodide [2] 6.309 0.0530 Hydrogen selenide: 5.338 0.04637 Hydrogen sulfide: 4.490 0.04287 Isobutane [2] 13.32 0.1164 Iodobenzene: 33.52 0.1656 Krypton: 2.349 0.03978 Mercury: 8. ...
Chromate and hydrogen chromate have equal concentrations. Setting [CrO 2− 4] equal to [HCrO − 4] in eq. 1, [H +] = 1 / K 1 , or pH = log K 1. This relationship is independent of pCr, so it requires a vertical line to be drawn on the predominance diagram. Red line Hydrogen chromate and dichromate have equal concentrations.
Pourbaix diagram of iron. [1] The Y axis corresponds to voltage potential. In electrochemistry, and more generally in solution chemistry, a Pourbaix diagram, also known as a potential/pH diagram, E H –pH diagram or a pE/pH diagram, is a plot of possible thermodynamically stable phases (i.e., at chemical equilibrium) of an aqueous electrochemical system.